The device of the present invention pertains to a stopcock capable of withstanding gamma radiation. The stopcock is constructed and arranged for high pressure applications.
Gamma radiation is a form of energy capable of deep penetration. Gamma irradiation is the use of gamma radiation to sterilize medical devices. Gamma radiation kills microorganisms throughout a product and its packaging with very little heating. As a sterilant, gamma radiation is thorough; no area of the product, its components, or packaging is left with uncertain sterility after treatment. Furthermore, gamma irradiation leaves no residue.
Traditional sterilization techniques include batch sterilization using ethylene oxide (EtO). EtO sterilization leaves a residue and requires an aeration period prior to shipment. The packaging must be gas permeable to allow the EtO to completely evaporate prior to use. Gas permeable packaging, however, increases the possibility of contamination over time. Thus, a relatively early expiration date is assigned to the sterilized device. Gamma radiation, on the other hand, penetrates through the packaging and, again, leaves no residue.
Commercially-available stopcocks, however, are constructed of materials that are not dimensionally stable when exposed to gamma radiation. Gamma-stable materials are more expensive and more rigid than the softer materials used to form the valve members of the commercially-available stopcocks. FIG. 1 shows a cross-sectional view of a typical, commercially-available stopcock 1. The stopcock 1 includes a valve member 3 inserted into a housing 5. The valve member 3 may be hollow, as shown, or solid and includes a port 7 that can be aligned with passage 9 of the housing 5.
The two-piece construction of the stopcock 1 relies on an interference fit between the valve member 3 and the housing 5. In other words, the valve member 3 is slightly larger than the interior of the housing 5. When the valve member 3 is inserted into the housing 5, it compresses and forms a fluid-tight fit. Thus, the valve member 3 must be constructed of a softer plastic than that of the housing 5. Typical materials used to make these valve members 3 include acetal and acrylonitrile butadiene-styrene (ABS).
Unfortunately, these soft materials used to make the valve members 3 cannot withstand gamma irradiation. When exposed, the valve members 3 change dimension and render the stopcock unusable. Thus, a less effective, more expensive, form of sterilization must be used.
Another disadvantage of these stopcocks 1 pertains to the design of the snap fit between the soft valve member 3 and the housing 5. As seen in FIG. 1, the snap fit arrangement is achieved by providing an angled flange 11 at the lower end of the valve member 3 that is configured to mate with a corresponding inwardly-projecting flange 13 that is integral with the housing 5. To allow assembly and a fluid tight fit, the flanges 11 and 13 have to be relatively small so that the flange 11 on the valve member 3 may deform and reform as it passes over the other flange 13 during assembly. The size relationship between the two flanges 11 and 13 limits the use of these stopcocks 1 for high pressure applications. When subjected to high pressures, there is a tendency for the valve members 3 to be ejected from the housing 5.
A further disadvantage of these stopcocks 1 is that they require excessive turning force to open and close the valves. Because the fluid-tight integrity depends on the friction fit between valve member 3 and the housing 5, and thus the valve member 3 is slightly larger than the housing 5, it is difficult to turn the valve member 3 within the housing 5. Users complain that two hands are necessary to operate the stopcocks 1 without causing the tubing attached to the stopcocks from becoming twisted or dislodged. Further, the relatively small size of the stopcocks 1 make it difficult to grasp the housing 5, to turn the valve member 3, without having fingers interfere with the handle of the valve member 3. This problem is especially prevalent when turning the valve members 3 of high pressure stopcocks while wearing wet rubber gloves.
Additionally, materials like acetal and ABS are opaque, which is yet another disadvantage. For purposes of blood and bubble detection, it is preferable to use a fluid network comprised entirely of clear components.
There is thus a need for a stopcock that can withstand gamma irradiation.
There is a further need for a stopcock that is constructed and arranged to withstand high pressures.
There is also a need for a stopcock that can be opened and closed with relative ease.
There is an additional need for a stopcock that is constructed entirely of clear materials.